1. Field of the Invention
The invention relates to a writing appliance comprising a shell tapered at one end, at the other end of which a reciprocable operating member is provided that can cooperate with the means housed in the shell, in order to bring a stylus provided in the shell in the operating position against the action of a spring acting on this stylus and to keep it in that position, or to bring the stylus in the nonoperating position and to keep it in that position, respectively.
2. Description of the Prior Art
Such a writing appliance is among others known from the Dutch patent application No. 278,392, whereby the means mentioned are formed by a cam movable in a longitudinal direction of the shell, which is connected to the operating member, and a ring rotatable around the centre line of the shell, with recesses along the edge opposite the operating member.
In the non-operating position, of the device of the prior art the cam rests in a deep recess of the ring. In bringing the stylus into the operating position, the cam moves out of the recess, when leaving the recess the ring rotates over a small distance and when the operating member is released the cam strikes the lower side of the ring, this lower side being of a sloped step construction. The cam slides over the upper slope along the ring till against the stop formed by above mentioned step. The stylus is now in the operating position. In order to bring the stylus in the non-operating position again, the operating member is pushed in again, the cam is released from said stop and the ring is slightly rotated.
When releasing the operating member of the known device the cam slides over said slope till it snaps in the adjoining deep recess, which recess corresponds with the first mentioned deep recess.
This known mechanism is rather complicated and expensive. It is housed in a shell in which little space is available. If there is more space available in the shell, as e.g. in constructions with an oval, triangular or square cross section or a shell with a large round cross section, then abovementioned mechanism can be simplified to a great extent and therefore becomes less expensive.